Systematic analysis of hydrophobin genes and heterologous characterization of a key hydrophobin Hyd15 in the culinary-medicinal mushroom Pleurotus tuber-regium.
Abstract
Hydrophobins are small, surface-active proteins that play essential roles in fungal development and have attracted industrial interest due to their self-assembly. Pleurotus tuber-regium (Fr.) Singer is a rare, thermotolerant, edible and medicinal macrofungus capable of forming sclerotia. Both its fruiting bodies and sclerotia are edible. However, the hydrophobins of this species remain largely uncharacterized. In this study, 32 hydrophobin genes were identified and the DNA and coding sequence (CDS) of 31 hydrophobin genes were successfully cloned from P. tuber-regium. Their gene structures, conserved domains, subcellular localization, signal peptides, amino acid properties, and phylogenetic relationships were predicted. The transcriptional profile of 31 hydrophobin genes in the entire growth cycle of P. tuber-regium was analyzed based on transcriptomics. In addition, the physiological roles of these hydrophobins were inferred. A key hydrophobin gene evm.model.contig_18_pilon.15 (hyd15), which is potentially involved in growth and development of P. tuber-regium, was selected for heterologous expression in Escherichia coli BL21(DE3). The recombinant Hyd15 protein could deposit on the silicon wafer surface and alter the hydrophilicity/hydrophobicity of an interface, as confirmed by X-ray photoelectron spectroscopy (XPS) and water contact angle measurements. Furthermore, recombinant Hyd15 exhibited emulsifying property superior to that of sodium caseinate. This study expands our understanding of the physiological functions of hydrophobins from mushrooms and provides a basis for their applications as natural surface-modifying and emulsifying agents.
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